Hydraulically operated automatic clutch control device for automobile vehicles



A. HYDRAULICALLY OPERATED AUTOMATIC CLUTCH CONTROL DEVICE Aug. 2l, 1956 BRUEDER FOR AUTOMOBILE VEHICLES Filed Dec. 17, 1953 United States Patent O HYDRAULICALLY OPERATED AUTOMATIC CLUTCH CONTROL DEVICE FOR AUTOMO- BILE VEHICLES Antoine Broeder, Paris, France, assignor to Societe Anonyme Andre Citroen, Paris, France, a corporation of France Application December 17, 1953, Serial No. 398,818 Claims priority, application France December 24, 1952 7 Claims. (Cl. 192-91) =This invention relates to a hydraulically operated control device for automatically effecting the engagement and disengagement of a friction clutch of an automobile engine, in a progressive manner such as is norm-ally required for these operations.

In order to enable these engaging and disengag-ing operations to be correctly carried out, it is necessary for the engine to be completely disconnected at a speed slightly greater than the idling speed, and to be completely engaged at a speed of the order of 1,200 R. P. M., for example. Between these two limits, there is an intermediate zone in which the operation must be effected very progressively. The pressure of the clutch springs on the clutch disc should therefore be a function of the vspeed of rotation of the engine, without-involving jerks or a time lag.

A control device made in accordance with the present invention comprises one hydraulic circuit including means for acting on the clutch springs in order to disengage the clutch, and a distributor controlled by a second hydraulic circuit placed .under pressure by a pump which is actuated by the engine and is arranged so that the delivery pressure is proportional to the speed of rotation of the engine, the arrangement being such that according to the speed of the engine the distributor places the member of the first circuit acting on the clutch in communication either with a pressure accumulator in order to disengage the clutch, or with a liquid reservoir in order to enable the vengagement to be effected by the Iact-i-on of the clutch springs.

According to a preferred form of construction, the distributor, connected to a reservoir und-er pressure, to a tank of liquid, and to a cylinder fitted with a piston acting by a suitable arrangement of levers on the clutch springs, comprises a slide valve, one end of which is subject to the pressure prevailing in the said cylinder and the other end of which bears against the bottom of a movable pist-on subjected on the one side, to the action of a compression spring, and, on the other side, to the action of the fluid delivered by the pump operated by the engine.

According 4to a more particular feature of the invention, there is provided in parallel, on the delivery side of the pump circuit, a restriction or jet, so that the delivery pressure obtained is strictly proportional to the engine speed.

Other features and advantages of the invention will be explained in the following description of the constructional form of the invention illustrated diagrammatically and by way of example only in the accompanying drawing.

As shown in the drawing, the apparatus comprises a reservoir or tank 1 of liquid supplying on one side a pressure accumulator 2, through the intermediary of a pump 3, and on another side a pump 4 operated directly by the engine, the arrangement being such that its derlivery pressure is proportional to the speed of rotation of the engine. To this end, there is provided a jet 5 2,759,584 Patented Aug. 21, 1956 ICC mounted in parallel .with a. pipe 6 connecting the pump 4 to a cylinder 7. The cylinder 7 contains a piston 8 and a compression'spring 9 acting on one surface thereof. The other surface of the piston is exposed to the pressure of the uid compressed by the pump and passing through the pipe 6.

r Below the cylinder 7 is disposed a distributor 10 connected to the reservoir 1 by a pipe 11, to the accumulator 2 by a pipe 12, and finally to a cylinder 114 by the pipe 13. The distributor is constituted by a body having a bore 15 communicating with the pipes 1l1, 12, 13 above referred to, and having a slide valve 16 slidably mounted therein. rIlhe slide valve 1'6 is of cylindrical shape,- the central part 17 being of reduced diameter by means of which either the pipes 12 and 13 or the pipes 1-1 and 13 can be placed in communication, according to the position of the valve. The latter bears permanently, as will be explained hereafter, againstl the bottom of the piston 8, the upper part of the bore 15 communicating with the cylinder 7, and its lower part with the pipe 13, by means of a by-pass 13.

In the cylinder 14 is slidatbly mounted a piston 18, with its rod 119 bearing on the end of a lever 20 pivotally mounted on a xed pin 21. The central part of this lever 20 bears on a ring or oscillating arms 22, which, in their turn, bear on the rim of a ring 23 rigidly connected with the primary shaft 214. The ends of the arms Z2 cooperate with rods 25 fixed to the clutch disc 26 on which act the springs Z7 bearing on Ithe ring 23. Facing the disc 26 is a second clutch dis-c 28 rigidly connected with the secondary shaft 29.

A one way valve, comprising a ball 30 pressed by a spring 31, is disposed between the cylinder 7 and the pipe 1'1 passing to the reservoir, in order to limit the pressure prevailing in the cylinder 7 -to a given value.

Finally, in order to provide, if desired, for starting by pushing the vehicle, a draw bar 32 is itted to overcome the action of the spring 9.

The operation of the device above described is as vfolliows:

Assuming the engine has stopped, the pressure of the pump 4 will be zero, and the spring 9 of the piston 8 will press into the bottom position the slide valve 1K6 of the distributor 10, thereby placing the hydraulic accumulator 2 in communication with the cylinder 114 off the piston 18 actuating the clutch lever 20, as a result of which the arms 22 pivoting on the ring 23, exert a pull on the rods 2S holding the disc 216 back against the action of the springs 27. The clutch elements are then in the disengaged position.

As s-oon as the engine is started, a pressure is set up in the delivery pipe 6 of the pump 4. The dimensions of the jet 5 and the characteristics of the spring 9 are so designed that, under the action of this pressure, the piston 8 is pressed back (at approximately 800 R. P. M. for example), by an amount sufficient for the slide valve 16, the bottom of which is subject to the pressure prevailing in the pipes 12 and 13, and therefore to that exerted by the clutch springs 27 in the cylinder 14, to close the commnnication between the accumulator 2 and the piston 18, and begin to place this latter in communication with the return to the reservoir 1, that is to say in position to initiate the engagement of the clutch.

When the engine is accelerated, the pressure supplied by the pump 4 increases and the exhaust of liquid from the cylinder 114 continues, under the action of the clutch springs lZ7.

lllf the engine has a tendency to slow down as a, result of the increase in the opposing torque, the reverse phenomenon is produced, i. e. the pressure falls below the piston 8, the latter drops under the action of the spring 9, the slide valve is brought into the position for disengaging the clutch.

As soon as 'the speed of the engine `is suioient, the

Inorder to describe the. operation further it mus-t iirst be observed that theA bottom ot the slide valve .16. is in communication `through. the .by-passy 113`I with the pipe Clv supplying the clutch disengaging cylinder 1.14, and receives therefore a thrust from lbottom. to. topi which is a funct-ion of the: tension 4of' the' clutch springs. As on its upper surface 'it receivesA a. thrust which is.` strictly a function of the engine 'speed there is constantly produced'. 'aposition of equilibrium which permits rapid disengagement, when` the engine has :a tendency to` s`ta11 :and which. permits a more or less progressive engagement according `to rthe In some, particular cases .it `is of advantage' to start an@ engine by allowing the. vehicle towfreeswheel downa grladient, or ibyv pushing4 lor towingv it, and, contraryev ltoythe :case of `a centrifugal clutch, this is made' possiblclwithr the'4 device accord-ing, to the invention.v It is: onlye necessary,

when the engine speed is considered to fbe-insuicient, to pull on the rod 32 yin order to eliminate the. actionfof the' spring 8.

I claim:

1. A hydraulically-'operated control device for. automatically effecting the selected engagement and.` disengage. mentof a [friction clutch` in a motor vehicleicomprising,"

in combination, a tirs-t hydraulic circuit including 'a source of uid, a ttrst pump and a pressure accumulator, and clutch-control means 'acted upon by the tluid infsaid. cir-- cuit for disengagng the .clutch when saidj tiuid. under pressure :is in communication with said clutch-control. means, said clutch being nonmallyf'engaged under theactionV of springs. and saidv clutch-control meansi effecting disengagement of' the clutch against the action'. of saidf springs, a

said distributor to close the path of communication between said rst circuit fand said clutch-control means whereby said clutch -i's engaged upon increase of lfluid pressure in said second circuit.

g2. A hydraulically-operated control device as delined in claim l1, further comprising means defining a calibrated passageway in parallel with said second pump.

` 3 1 A hydraulically-operated control `device as `deiined in claim 1, wherein said distributor-control means includes a' cylinder in communication with the outlet of said second pumpl'and a 'springapressed piston slidably mounted insaid cylinder and normally urged against the pressure of the iiuid from said second pump.

4. A hydraulically-operated control device as. deiined in claim 3, wherein said distributor comprises means delining 'a cylinder chamber communicating withV said distributorcontrol cylinder yand `a cylinder slide valve slidably speed with which the accelerator of the. engine is.. operated-.

axially insaid distributor cylinder, one end of 'said slide valve being engageable with| said. spring-pressed piston, conduit means :connecting said distributor cylinder with said source Vof tluid, said pressure accumulator and said clutch-control means. l

5. A hydraulically-operated control device as `deined in claim` 1f,Wherei-n the clutch-control means comprises a cylinder communicating jat one: end ywith' said first circuit,

1 afpiston slidable in said cylinder, and a lever arm connected with said, piston for acting upon said clutch, said leverA disengaging said clutch against the. pressure of the clutch springs: when said. vpiston is urged forwardly in second fluid circuit connected withA said hydraulic uid! y source, said, second 'circuit includingV a second purn'p` driven by the engine of the.` motor vehicle to provide'a deliverypressure in said second circuit proportional tov-the speed of the engine, ay distributor-associated yvvi'thsaidl irst circuit 'for controlling the llow of rfluid to said clutchcontrol means, fand distributor-control means normally :acting upon said `distributor to provide communication-between said dirs-t circuit and said clutch-control means, vsaid sec.- Iond circuit communicating #with said vdistributor-control means to actuate said 'distributor-control means to release response teilnid pressurein said cylinder.

6.v Av hydraulically-operated control device as delined in claim 4, whereinv said slide valve is. provided with a restricted central portion for providing communication between said accumulator and said clutch-control means `when, said` slide valve is `in its lowermost position and wherein lsaid slidey valve provides communication between said accumulator andsai-d clutch-control means Whensaid slide'valve isinfits uppermost position.

v7. A .hydraulically-operated control device as deiined inyclaimf3, further comprising manual release means for eliminating theA 4spring pressure fon they pist-on of the `distributor-control means.

l'References Cited in the. le of this patent UNITED STATES PATENTS 1 999',366 Maybach Apr. 30; 1935 i' FOREIGN PATENTS `570,236- 'France Jan. 14, 1-924 

